    Active fragrance ingredient: in the context of this invention, this term designates any substance that has a detectable olfactory activity. For simplicity's sake, the Application may use the shortened expression “active ingredient” to refer to the “active fragrance ingredient”.    Perfume: in the context of this invention, this term designates any formulation that contains at least one active fragrance ingredient.    HASE: Anglo-Saxon acronym for Hydrophobically Alkali Swellable Emulsion. This term designates acrylic thickening agents based on (meth)acrylic acid, on an ester of these acids and on a hydrophobic monomer.